import sys


def input():
    return sys.stdin.readline()[:-1]


def main():
    s = int(input())
    if s >= 30:
        print('Yes')
    else:
        print('No')


if __name__ == "__main__":
    main() import sys sys def input():
    return sys.stdin.readline()[:-1] input return sys.stdin.readline()[:-1] sys.stdin.readline()[:-1] sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline :-1 -1 def main():
    s = int(input())
    if s >= 30:
        print('Yes')
    else:
        print('No') main s = int(input()) s int(input()) int input() input if s >= 30:
        print('Yes')
    else:
        print('No') s >= 30 s 30 print('Yes') print 'Yes' print('No') print 'No' if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    s = int(input())
    if s >= 30:
        print('Yes')
    else:
        print('No') def main():
    s = int(input())
    if s >= 30:
        print('Yes')
    else:
        print('No') main def input():
    return sys.stdin.readline()[:-1] def input():
    return sys.stdin.readline()[:-1] input
import sys


def input():
    return sys.stdin.readline()[:-1]


def main():
    s = int(input())
    if s >= 30:
        print('Yes')
    else:
        print('No')


if __name__ == "__main__":
    main()